Mid-Term Study Guide

Notes:

Regarding terms, you should know the definitions and concepts well enough to be able to answer "compare and contrast", "fill-in-the-blank", and "definition matching" questions.

This is not meant to be an exhaustive list of possible questions for the exam. It is meant to give you a general idea of the possible types of questions that might be asked and an idea of the topics I think are most important.

You should also study homework questions and problems that we've discussed during lectures.

Mid-Term Format

15 terms

10 short-answer

3 problems

Internet Applications

Terms:

phishing

spamming

computer virus

computer worm

Trojan horse

wiki

blog

What is one way to avoid spam?

Name one website you can use to check out hoaxes or urban legends.

How is a listserv different from a email distribution list that you setup in your mail reader?

What is the difference between true streaming and pseudo streaming?

Web Search and Access

Terms

deep crawling

fresh crawling

PageRank

Wayback Machine

What are the three main components of Google search?

What is '/robots.txt' and how can it be used?

How can a webpage author, not the website owner, control robots?

What file is used to specify the protection for a set of webpages?

Whirlwind Overview

Terms:

protocol

router

multiplexing

packet-switching

circuit-switching

out-of-band control vs. in-band control

push protocol vs. pull protocol

transmission delay

propagation delay

propagation speed

queuing delay

end-to-end delay

bandwidth-delay product

throughput

bottleneck link

Why would it be better to use packet-switching instead of message-switching (assuming that packets are much smaller than messages)?

What are 2 types of multiplexing in circuit switching?

What are the 5 TCP/IP protocol layers (in order)?

What are the 4 types of delay that a packet can encounter when traveling through a network? For a fixed path and fixed packet size, which are constant and which are variable?

What are three different transmission rates of Ethernet LANs?

Out of dial-up modems, cable modems, and DSL modems, which provide dedicated access?

What does it mean for a network to be store-and-forward?

What causes packet loss?

Given a set of links with different link speeds, indicate which is the bottleneck link.

Compute transmission delay given link speed and packet size.

Compute the propagation delay given propagation speed and physical distance.

Compute when bits of a packet arrive at the destination given link speed, propagation delay, and packet size.

Compute the bandwidth-delay product of a link given link speed and propagation delay.

Client-Server

Terms:

client

server

port

TCP

UDP

flow control

congestion control

What is the main difference between the operation of a client-server application and a peer-to-peer application?

What two elements are needed to address a communicating process?

What is the TCP 3-way handshake?

Do either of the Internet Transport Protocols (TCP, UDP) provide guaranteed delays or guaranteed bandwidth?

HTTP

Terms:

GET

HEAD

persistent connections

non-persistent connections

persistent connections with pipelining

HTTP/1.0

HTTP/1.1

browser cache

What is the default port used for HTTP servers?

Given a URL, identify the hostname and path.

Does HTTP use TCP or UDP? Why?

What is the typical application-level exchange for a HTTP/1.0 transfer?

What is the HTTP status code for a successful response?

What is the HTTP status code for a page that is not found?

How can a HTTP/1.0 transfer be made to use persistent connections?

Which are typically larger - HTTP requests or HTTP responses?

How does an HTTP client ask a server if a file has been modified?

Given a network topology, compute the total delay for a HTTP/1.0 request-response pair. Include all TCP-related operations (i.e., handshakes). Assume that the IP address is known.

List all TCP connections that would be needed to request a web page using HTTP/1.1 where the base page is at host1 and there are 3 embedded objects located at host1, host2, and host3, respectively.

Compute the minimum number of round-trip times (RTTs) needed to download all elements of a web page, given a network topology and number and size of embedded objects in the web page using non-persistent connections, persistent connections, and HTTP/1.1.

Securing the Web

Terms:

HTTPS

authentication

encryption

symmetric cryptography

asymmetric cryptography (or public-key cryptography)

certification authority

certificate

Decrypt a message using a simple Caesar cipher.

Explain how a Alice can digitally sign a message for Bob using public-key cryptography. The goal is for Bob to be sure that only Alice could have sent the message.

Why are trusted third parties, like certification authorities, necessary for public key cryptography?

How can you tell if a website is using the secure HTTP protocol, HTTPS?

FTP and Email

Terms:

user agent

mailbox

active FTP

passive FTP

How many connections are used simultaneously for correct FTP operation?